This invention relates to modes of stimulation including vibration, actuation and thermal stimulation in human-machine interfaces such as biomechanical communication and computer based gaming experience. Some aspects of the invention are applicable to medical and biomedical equipment for treatment, testing, or experimentation on sensory pain due to thermal stimulation. Other modes of stimulation including actuation and vibration for therapeutic and rehabilitation purposes are also applicable.
Vibratory and actuation stimulation for use in biomechanical communication such as vibration based message transmission, and human-machine interfaces such as enhanced experience during computer based gaming is a recognized need. Multi-point programmable stimulation on human body can be a very useful means for communication not only for persons challenged in receiving information through conventional visual or auditory means but also for general purpose applications. For example, there is emergence of vibratory tones in mobile phones to distinguish between the different callers so that the receiver of the call may identify the caller covertly without looking at the display of the mobile phone or listening to an auditory ring tone that disturbs others. In the gaming systems, there is growing need for increased sensory stimulation of different body parts of the gamers for multi-modal immersive feeling although currently the stimulation is mainly limited to joystick interfaces. Examples of these applications include vibration by means of eccentric motor actuators (Yoshida et al, U.S. Pat. No. 7,157,822; Tremblay et al, U.S. Pat. No. 6,275,213), piezoelectric actuators (Gouzman et al, U.S. Pat. No. 5,912,660; Kyung et al, U.S. Pat. No. 7,339,574), and pressurized fluid actuators (Roberts et al, U.S. Pat. No. 7,352,356). The motor based and piezoelectric actuators based array systems suffer from constraints in miniaturization due to minimum size of actuator elements that makes it difficult to embed them on a wearable substrate with the desirable flexibility and space resolution. The entire body of a motor vibrates instead of a desired specific area coming in contact with a human body. Piezoelectric elements that create enough perturbation are long strips required to be deposed in cantilever configuration for desired vibration near the tip. The pressurized fluid actuators based system requires a complex grid of valves for control of actuation, again imposing difficulty in miniaturization, embedding, and achievement of close spacing.
In the medical and biomedical field, application of a range of temperatures from cold to hot by contact of an embodiment on a human body part in order to find the sensory stimulus, and to measure the threshold of the thermal stimulus causing pain is a known requirement. U.S. Pat. No. 5,191,896 (Gafni et. al.) and the references listed therein, the contents of which are adopted herein in total by reference, describe in detail this requirement. U.S. Pat. No. 5,634,472 (Raghuprasad) claims a method of determining the severity of pain at a selected area of a person's body according to a series of steps. U.S. Pat. Nos. 6,113,552 and 7,399,281 (Shimazu et. al.) claim pain measurement systems that focus on electrical stimulus, not on thermal stimulus. The apparatus disclosed in the relevant prior patent (U.S. Pat. No. 5,191,896) applies the thermal stimulation by a single stimulator comprising one or more Peltier elements inside the stimulator. The apparatus has several limitations. The stimulator provides only a single embodiment in contact with the human body whereas recent research and efforts towards development of test-in-principle experimental set ups (e.g., Hunter et. al., Defrin et. al., Cohen et. al., Monbureau, Bouhassira et al, Craig et. al.) have shown a need for experimentation that has an array of several pixels in contact with the human body with a provision to vary temperatures of the pixels independently to form a pattern of different hot and cold temperatures concurrently. Yet another limitation is that the embodiment comprises heating elements arrangement that has constraints including lack of flexibility, and limitation in miniaturization. Further, the embodiment coming in contact with the human body is flat and rigid and thus can not be flexibly brought in contact with a curved surface of the body for assessing the effects of thermal stimulation on different locations of such curved surface simultaneously. Still another limitation of the prior art is that the distance between different points of hot and cold stimulus on human body can not be varied as the device has the stimulator with only a fixed single surface available for contact with the human body. In addition to the thermal stimulation for research in pain sensation, there is emerging potential for vibration stimulation for therapeutic and rehabilitation applications. Example of such application is Vibration Stimulation Therapy Apparatus, Its Use, Method, and Computer Program disclosed by Kawahira et al (PCT Pub. No. WO/2006/134999). However, the disclosure does not provide independently controllable multi-pixel stimulation compliant to curved surface using thermal means. Also, possibility to combine thermal and vibratory stimulation is not reported.
Aspects of the present invention overcome some of the difficulties in prior art either individually or in combination with each other. The advantages of the present invention will become apparent from the description and accompanying drawings.